我正在为学校作业编写图书馆管理程序，并不断收到细分错误。当我使用类函数（printBook()）来显示每本书的信息时，会发生错误。这个函数最初工作没有任何问题，但在我对程序的其余部分进行了一些更改后开始抛出错误。 printBook()函数没有改变（这是我写的第一件事之一，所以我可以看到一切都正常工作）。代码如下：
// ****************** Book class and associated code *************************
class Book{
private:
int id;
string title;
string author;
string category;
int numCopies;
public:
void newBook(int newID,string newTitle, string newAuthor, string newCategory, int copies);
//void editBook();
void loanBook(int bookID, int memID);
int getID();
string getTitle();
string printBook();
};
void Book::newBook(int newID, string newTitle, string newAuthor, string newCategory, int copies)
{
id = newID;
title = newTitle;
author = newAuthor;
category = newCategory;
numCopies = copies;
}
/*void Book::editBook()
{
}*/
int Book::getID()
{
return id;
}
string Book::getTitle()
{
return title;
}
string Book::printBook() //problem occurs when this function is called
{
cout << "ID: " << id << endl;
cout << "Title: " << title << endl;
cout << "Author: " << author << endl;
cout << "Category: " << category << endl;
cout << "Number Of Copies: " << numCopies << endl;
cout << endl;
}
// ****************** Collection class and associated code *************************
class Collection{
private:
Book bookArray[1000];
int index;
public:
Book search(int bookID);
Book search(string bookTitle);
int generateNewID();
void setIndex(int x);
int getIndex();
string getTitle();
void addToCollection(Book newBook);
void printCollection();
};
Book Collection::search(int bookID)
{
for(int i = 0; i < index; i++)
if(bookArray[i].getID() == bookID)
return bookArray[i];
}
Book Collection::search(string bookTitle)
{
for(int i = 0; i < index; i++)
if(bookArray[i].getTitle() == bookTitle)
return bookArray[i];
}
int Collection::generateNewID()
{
for(int i = 0; i < index; i++)
if(bookArray[i].getID() != i)
return i;
}
void Collection::setIndex(int x)
{
index = x;
}
int Collection::getIndex()
{
return index;
}
void Collection::addToCollection(Book newBook)
{
bookArray[index] = newBook;
index++;
//sorts bookArray by the id each time a new book is added to the bookArray
for (int i = 0; i < index; i++)
for(int j = 0; j < index; j++)
if(bookArray[i].getID() < bookArray[j].getID())
{
Book temp = bookArray[i];
bookArray[i] = bookArray[j];
bookArray[j] = temp;
}
}
//This calls the printBook() function so it also throws the error
void Collection::printCollection()
{
for(int i = 0; i < index; i++)
bookArray[i].printBook();
}
// ****************** Function Declarations *************************
// ******************************************************************
int main()
{
bool run = true; //used to keep program looping to main menu
ifstream collectionFile;
collectionFile.open("books.txt"); // books are saved in this file
Collection collection;
collection.setIndex(0);
Book book;
Book searchResult;
int menuSelection;
int a, e; //a = id, e = copies
string b, c, d; //b = title, c = author, d = category
if(collectionFile.is_open())
{
while(collectionFile >> a >> b >> c >> d >> e)
{
cout << a << ", " << b << ", " << c << ", " << d << ", " << e << endl;
book.newBook(a, b, c, d, e);
collection.addToCollection(book);
}
}
else
cout << "File not found" << endl;
cout << "****************************************************************************" << endl;
cout << "***************** ABC University Library Management System *****************" << endl;
cout << "****************************************************************************" << endl;
cout << endl;
cout << endl;
while(run)
{
cout << "Please make a selection by entering the number next to your selection: " << endl;
cout << "1. Add new book" << endl;
cout << "2. Edit a book" << endl;
cout << "3. Get books on loan to member" << endl;
cout << "4. Print out overdue books" << endl;
cout << "5. Print the collection" << endl;
cout << "6. Exit" << endl;
cout << "# of books in collection: " << collection.getIndex() << endl;
cin >> menuSelection;
switch(menuSelection)
{
bool valid;
char validationInput;
int searchInt;
case 1:
do
{
cout << "Enter the title: " << endl;
cin >> b;
cout << "Enter the author: " << endl;
cin >> c;
cout << "Enter the category: " << endl;
cin >> d;
cout << "Enter the number of copies: " << endl;
cin >> e;
cout << "You have entered :" << endl;
cout << b << ", " << c << ", " << d << ", " << e << endl;
cout << "Is this correct? (Enter 'Y' or 'N')" << endl;
cin >> validationInput;
validationInput = (char)toupper(validationInput);
if(validationInput == 'Y')
valid = true;
else
valid = false;
}
while(!valid);
book.newBook(collection.generateNewID(),b,c,d,e);
collection.addToCollection(book);
cout << "You have added the book: " << endl;
book.printBook(); // error here
break;
case 2:
do
{
cout << "Do you know the ID number of the book you would like to edit? (Enter 'Y' or 'N')" << endl;
cin >> validationInput;
validationInput = (char)toupper(validationInput);
if(validationInput == 'Y')
{
cout << "Please enter the book ID of the book you would like to edit: " << endl;
cin >> searchInt;
searchResult = collection.search(searchInt);
searchResult.printBook(); //error here
}
}
while(!valid);
break;
case 5:
collection.printCollection(); //error here
break;
case 6:
cout << "Thank you for using the ABC University Library Management Program!" << endl;
run = false;
break;
default:
cout << "Invalid Selection";
break;
}
}
return 0;
}
我评论了使用printBook()的行。感谢您的帮助。
答案 0 :(得分：2)
正如我的评论一样，它看起来与printBook的返回类型string有关，但你没有返回一个值。返回类型应该是void。